In the ten years of its existence, the Group Theatre produced works by many important American playwrights, including Clifford Odets, Sidney Kingsley, Paul Green, Robert Ardrey, and Irwin Shaw.

The Group Theatre included Harold Clurman, Lee Strasberg, Cheryl Crawford, Stella Adler (a founding member), Morris Carnovsky, Clifford Odets, Sanford Meisner, Elia Kazan, Harry Morgan (billed as Harry Bratsburg), Robert Lewis, John Garfield (billed as Jules Garfield), Canada Lee, Franchot Tone, Frances Farmer, Phoebe Brand, Ruth Nelson, Will Geer, Howard da Silva, Sidney Lumet, John Randolph, Joseph Bromberg, Michael Gordon, Paul Green, Marc Blitzstein, Paul Strand, Anna Sokolow, Lee J. Cobb, Roman Bohnen, Jay Adler, Luther Adler, Robert Ardrey, Don Richardson and many others.

[citation needed] Elia Kazan directed Robert Ardrey's plays Casey Jones and Thunder Rock in 1938 and 1939–40 for the Group Theatre.

[18] Despite its success and sweeping impact on the American theater landscape for many years to come, the group ended by 1941, and factors included the impending war, the lure of fame and fortune in Hollywood, the lack of institutional funding, and the friction of interpersonal relationships.

[19] After the war, in 1947, Robert Lewis, Elia Kazan, and Cheryl Crawford founded the Actors Studio, where the techniques inspired by Stanislavski and developed in the Group Theatre were refined.

Under the leadership of Lee Strasberg, who later joined the Actors Studio and became its director in 1951, what is now referred to as The Method emerged as a lasting force in modern drama.

Those who appeared as friendly witnesses, such as Elia Kazan, Clifford Odets, and Lee J. Cobb, avoided the fate of their colleagues who refused to name Communist Party members and, as a result, were blacklisted.

Elia Kazan would later state he abandoned his Communist views in part because of an agenda to transform the Group Theatre into a company devoted to promoting "Marxist ideology."